Typical photographic elements use silver halide emulsions, the silver halide having a native sensitivity to ultraviolet radiation. Ultraviolet radiation ("UV") as used in this application means light having a wavelength of 300-400 nm. Such UV sensitivity is usually undesirable in that it produces an image on the photographic element which is not visible to the human eye. Furthermore, the image dyes in the color photographs are known to fade due to action of UV light. Also other organic molecules such as unused color forming couplers in the emulsion layers and optical brighteners in the paper support degrade due to action of UV light and generate undesirable color stains on the finished photographs. Therefore, photographic elements typically contain a UV absorbing compound (sometimes referred to simply as a "UV absorber"). Another function of UV absorbers is to prevent the formation of undesirable patterns caused by electrostatic discharge in silver halide photographic materials. In general, UV absorbers impart light stability to organic molecules in various products which are susceptible to degrade as a result of the action of UV.
Generally, an effective UV absorber should have its peak absorption above a wavelength of 320 nm. The absorption peak may be at a longer wavelength, as long as absorption drops off sufficiently as it approaches the visual range (approximately 400 to 700 nm) so that no visible color is shown by the compound. In addition, to be effective, a UV absorber should have a high extinction coefficient in the desired wavelength range. However, for the most desirable UV protection, the high extinction coefficient should be at those wavelengths sufficiently below the visual range so that the compound should not be visually yellow.
UV absorbers of the benzotriazole class for photographic and other applications are well known. They include hydroxyphenyl benzotriazoles with various substituents on the hydroxyphenyl ring, including alkoxy. Compounds of the foregoing type are disclosed, for example, in Japanese published patent application JP 3139589. U.S. Pat. No. 5,112,728 discloses photographic elements with liquid hydroxyphenyl benzotriazole UV absorbers, including one example which incidentally has a racemic carbon center. Also, U.S. Pat. Nos. 4,975,360; 4,973,701 and 4,996,326 all disclose photographic elements which contain liquid hydroxyphenyl benzotriazoles as UV absorbers. U.S. Pat. Nos. 4,973,701 and 4,992,358 discuss various advantages of the absorbers being liquid. Some of the compounds in those patents include substituents on the hydroxyphenyl ring which incidentally have a racemic carbon center.
2-Hydroxyphenyl benzotriazole UV absorbers with a large class of acylamino groups, including carbamates, sulfonamides, and many others, are described in FR 1,330,378, FR 1,324,898, FR 1,324,897, GB 991 204, GB 991 320, GB 991 142, GB 991 630, and GB 991 204. However, none of the compounds disclosed in those references provide a carbamate with an asymmetric carbon.
UV absorbers which are currently used in photographic products include those of formula (II-A) and (II-B) below: ##STR2## However, compounds (II-A) and (II-B) have a propensity to crystallize out during cold storage of a dispersion of them.
It is therefore desirable to have other UV absorbing compounds suitable for photographic uses, which are relatively stable in a photographic environment, and in particular have a low tendency to crystallize out at ordinary temperatures at which photographic elements are used and/or stored, which have a high extinction coefficient so that less of it needs to be used to obtain the same UV absorption, and which have a good UV absorption spectrum for photographic uses.